Juniper Networks Enterprise Routing and Switching, Professional (JNCIP-ENT, JN0-650) (JNCIP-ENT) (JNCIP-ENT) — Questions 226–264

The transmit-rate parameter sets the minimum guaranteed bandwidth for a queue, ensuring the best-effort queue receives its allocated share even under congestion. Configuring transmit-rate prevents starvation by reserving capacity, whereas other scheduler parameters only influence excess-bandwidth distribution or buffer behaviour.

By default Junos only compares MED between paths from the same neighbouring AS, so MEDs from different autonomous systems are ignored. Configuring always-compare-med under protocols bgp forces Junos to evaluate MED across all paths regardless of originating AS, satisfying the scenario's cross-AS comparison requirement.

Type-4 Ethernet Segment routes carry the ESI and DF election capability, letting PE routers run the DF election algorithm per Ethernet segment. This satisfies the all-active requirement that only one PE forwards BUM traffic for a given segment, preventing duplicate flooded frames while all PEs remain active for known unicast.

Both route reflectors are configured with the same cluster ID (10.0.0.1), so when the client reflects the route, the CLUSTER_LIST contains 10.0.0.1. When 10.0.0.2 receives the update, it detects its own cluster ID in the CLUSTER_LIST and discards the route, preventing a routing loop within the cluster. This is the standard BGP route reflection loop-prevention mechanism.

EVPN routes such as MAC/IP advertisement and IMET are carried in the BGP EVPN address family, enabled as evpn signalling under the neighbour hierarchy. The inet or inet6 families carry unicast IP routes only, so they cannot distribute EVPN NLRI between PE routers.

Mesh groups allow a set of MSDP peers to fully mesh logically; SA messages received from a mesh group peer are not flooded to other members of the same mesh group, preventing loops.

MSTP boundary ports receive RSTP BPDUs and fall back to RSTP compatibility on that port only, allowing interworking with legacy RSTP switches on shared segments while preserving MSTP operation internally. Compatibility is per-port, not region-wide.

The VTEP source address is typically a loopback interface address, which ensures high availability and stability. It must be reachable via the underlay network so that remote VTEPs can establish VXLAN tunnels. This is a standard best practice for EVPN-VXLAN deployments on Junos.

A 'Hardware error' PoE status indicates the port's power controller or the supplying PSU cannot deliver power, so verifying chassis power and PoE controller health isolates whether the fault is internal hardware rather than the phone or cabling.

Type 2 advertisements bind a tenant MAC to its associated IP in one NLRI, letting remote PEs install both bridging and routing entries from a single BGP update rather than separate MAC and ARP/ND messages.

Junos installs multiple BGP paths for a prefix only when they are equal-cost: identical AS path length, local preference, origin and MED. If any of these attributes differ, path selection picks a single best route and multipath remains inactive despite the configuration.

In Junos EVPN, each bridge domain maps its VNI under the bridge-domains hierarchy within the routing instance. Placing vni at that level binds the layer-2 domain to its unique EVPN identifier, satisfying the one-VNI-per-bridge-domain requirement.

EVPN MAC mobility relies on sequence numbers carried in Type-2 (MAC/IP Advertisement) routes, allowing every PE to determine the most recent advertisement for a given MAC. When a host moves to another PE, the higher sequence number wins, so stale entries are withdrawn and traffic follows the host, satisfying the requirement to track movement between PEs.

224.0.0.1 is the all-hosts group on a local subnet, which every IPv4 host joins automatically. Routers send IGMP general queries to this address to poll all hosts, satisfying the stem's requirement for querying every host on the local segment.

The area-range statement under the area configuration on an ABR summarizes routes from that area into other areas. Configuring area-range under area 1 will summarize the routes from area 1 into area 0. This is the correct way to perform inter-area route summarization in OSPF on Junos.

The `database-overflow limit` parameter caps external LSAs at 5000, triggering overflow state once exceeded, while `external-timer 300` holds the router in that state for 300 seconds before retrying. This directly satisfies the stem's requirement to prevent memory exhaustion from excessive external LSAs, applied globally under `protocols ospf`.

The no-translate option on the NSSA ABR stops that router translating Type-7 LSAs into Type-5, leaving translation to the other ABR. This prevents duplicate Type-5 LSAs flooding the backbone, satisfying the requirement to suppress translation on one ABR.

PIM hello messages build neighbour adjacencies, and joins only propagate once these exist. The show pim neighbor command displays each neighbour's address, interface, uptime and holdtime, confirming whether hellos are being exchanged and revealing why join messages never reach the Rendezvous Point.

Switches are in the same MST region only when their MST configuration identifier matches exactly: the region name, the revision number, and a digest of the full VLAN-to-instance mapping table, which is carried in BPDUs. One VLAN mapped differently, even an unused one, puts a switch in another region. On Junos, compare 'show spanning-tree mstp configuration' across switches, checking the name, revision and digest.

The 'summary-only' parameter suppresses specific component routes when advertising the aggregate prefix.

A strict-high priority scheduler services the video queue ahead of all other queues whenever packets are present, giving the multicast stream the lowest possible latency and jitter even under congestion. Junos guarantees the strict-high queue is drained before other queues are scheduled, which directly satisfies the requirement without dropping the other classes entirely.

IGMPv3 membership reports carry source filtering, letting hosts specify include (TO_IN, IS_IN) or exclude (TO_EX, IS_EX) source lists. Earlier versions only supported group joins without source selection, so IGMPv3 uniquely satisfies the explicit inclusion and exclusion requirement.

Multiple supplicant mode allows multiple devices on a single interface to be authenticated individually. Each device undergoes its own 802.1X authentication, and upon success, can be assigned to a specific VLAN via RADIUS attributes. This is exactly what is needed for a hub with three devices. The interface must be configured with 'supplicant multiple' under the 802.1X settings.

If the RPF lookup resolves to a reject or discard route, the RPF check fails.

In Junos BGP path selection, the AS path length is compared before MED. Peer B has an AS path length of 2, which is shorter than Peer A's length of 3. Therefore, Peer B's path is preferred, and MED is not considered. This is the correct order unless additional configuration changes the default behavior.

When a multi-homed PE receives BUM traffic from its own Ethernet segment, the receiving PE checks the ESI label; split horizon filtering drops frames whose ESI label matches the local segment, preventing the loop back to the originating PE.

Walled garden or firewall exemption filters let the switch permit pre-authentication traffic to specified destinations, such as DNS, DHCP and critical server subnets, while still forcing all other client traffic through the captive portal authentication process.

Weight is evaluated first in Junos BGP path selection.

LLDP-MED network policy TLVs are only transmitted when a policy is explicitly configured under the lldp-med hierarchy. Enabling lldp-med on the interface alone advertises capabilities and inventory, but no voice VLAN or Layer 2/3 priority data. Creating a network policy with application type voice, the target VLAN ID, and the desired DSCP/CoS mapping gives the phone the exact parameters it needs to tag frames and join the voice VLAN.

To advertise the voice VLAN to LLDP-MED capable phones, you must configure a network policy that specifies the application type as 'voice' and the VLAN ID. This policy is then sent in LLDP-MED TLVs, allowing the phone to automatically tag voice traffic with the correct VLAN. Without this, the phone will not receive the VLAN information and may not function correctly on the voice VLAN.

Rewrite rules that remark DSCP on egress are configured under [edit class-of-service interfaces] on the outbound interface, where the scheduler maps forwarding classes to rewrite values. Applying it at the interface level ensures the remarking occurs as packets leave.

EAPOL-TIMEOUT means the switch transmitted an EAPOL request (typically Identity or Request) to the supplicant and received no reply within the retransmission window, so the authenticator times out the session. It does not indicate a credential or RADIUS failure.

In class mode the switch reserves power per port based on the advertised class, and if the total reserved power exceeds the available PoE budget, later ports may be powered briefly and then dropped, causing a boot loop. Checking the budget and the sum of reservations identifies this condition, and adding power or reducing powered ports restores stable operation.

The cluster ID identifies the route-reflection cluster, and every route reflector within it must share the same value. When a route reflector receives an update carrying its own cluster ID in the CLUSTER_LIST attribute, it discards that route, preventing loops between redundant reflectors. Differing cluster IDs would defeat this loop detection.

MAC-RADIUS combines MAC address authentication with RADIUS, letting the switch authenticate a device by its MAC before any 802.1X supplicant responds. This satisfies the stem's requirement for a valid authentication-order method, since Junos accepts mac-radius alongside dot1x, captive-portal and mac-radius-restrict on EX Series interfaces.

MC-LAG with ICCP lets two Juniper devices present one logical LAG to the access layer, giving Active-Active multihoming with no blocked links. ICCP synchronises state between peers, so the core needs no Spanning Tree Protocol to prevent loops.

Exceeding the reuse threshold triggers route re-advertisement, but the penalty keeps decaying exponentially toward zero rather than resetting. The stem's constraint concerns post-reuse behaviour, and Junos applies the same exponential half-life decay throughout suppression and after unsuppression, so the penalty only reaches zero once sufficient time elapses.

This is correct. BPDU guard, when enabled on an edge port, disables the port upon receiving a BPDU, placing it in err-disabled state. Junos OS supports automatic recovery from err-disabled state via the 'errdisable recovery' configuration, which can re-enable the port after a timeout.

Only the PIM Designated Router (DR) on the source LAN sends Register messages to the RP. If the FHR is not the DR, it will not send registers. The DR is elected based on PIM priority and highest IP address; if another router is DR, the FHR will not perform registration.